Yet the men who framed this declaration were great men—high in literary acquirements—high in their sense of honor, and incapable of asserting principles inconsistent with those on which they were acting. –Dred Scott v. Sandford,
Supreme Court of the United States

How does Taney use this appeal to emotion to support his argument?

The appeal praises the virtues of the writers of the document Taney uses as evidence.
The appeal relies on his original claim that Dred Scott is not a citizen and cannot sue in a federal court.
The appeal counters Taney’s claim that people’s origins dictate their status in the community.
The appeal creates doubt about the validity and soundness of the Constitution in terms of defining citizenship.